Re: Realtek 8139 problem on 486.

[Denis Kirjanov <kda@linux-powerpc.org>]

On 5/29/21, Nikolai Zhubr <zhubr.2@gmail.com> wrote:
> Hello all,
>
> I'm observing a problem with Realtek 8139 cards on a couple of 486
> boxes. The respective driver is 8139too. It starts operation
> successfully, obtains an ip address via dhcp, replies to pings steadily,
> but some subsequent communication fails apparently. At least, nfsroot is
> unusable (it gets stuck in "... not responding, still trying" forever),

What's your qdisc? Recently there was a bug related to the lockless
pfifo_fast qdisc

> and also iperf3 -c xxx when run against a neighbour box on a lan prints
> 2-3 lines with some reasonable 7Mbit/s rate, then just prints 0s and
> subsequently throws a panic about output queue full or some such.
>
> My kernel is 4.14.221 at the moment, but I can compile another if
> necessary.
> I've already tried the "#define RTL8139_DEBUG 3" and "8139TOO_PIO=y" and
> "#define RX_DMA_BURST 4" and "#define TX_DMA_BURST 4" (in case there is
> a PCI burst issue, as mentioned somewhere) and nothing changed whatsoever.
>
> Some additional notes:
> - the problem is 100% reproducable;
> - replacing this 8139 card with some entirely different 8139-based card
> changes nothing;
> - if I replace this 8139 with a (just random) intel Pro/1000 card,
> everything seem to work fine;
> - if I insert this 8139 into some other 486 motherboard (with a
> different chipset), everything seem to work fine again;
> - etherboot and pxelinux work fine.
>
> I'm willing to do some debugging but unfortunately I'm not anywhere
> familiar with this driver and network controllers in general, therefore
> I'm asking for some hints/advice first.
>
>
> Thank you,
>
> Regards,
> Nikolai
>